Rodents have been accused of everything from the Black Death to electrical fires over the centuries – now climate change can be added to the long list of mishaps for which they are to blame.
Two new studies have found that the Arctic ground squirrel and the beaver are contributing far more to global warming than previously thought, suggesting that they are a major contributor to climate change.
The first study, by the Woods Hole Research Centre in Massachusetts, reveals that Arctic squirrels are hastening the release of the greenhouse gases methane and carbon dioxide by melting the permafrost that has kept dead animals and vegetation preserved underground for years.
They do this, in part, by warming the frozen soil when they dig burrows, helping to accelerate the melting of the permafrost.
Their faeces and urine further contribute to the process, fertilising the soil, which nourishes the microbes that create methane by decomposing the dead organic matter and releasing it into the atmosphere.
“It certainly has a bigger impact than we’ve considered and it’s something we will be considering more and more going into the future,” said Dr Sue Natali, of the Woods Hole Research Centre. “Carbon has been accumulating in permafrost for tens of thousands of years. The temperature is very cold, the soils are saturated, so that when plants and animals die, rather than decompose, the carbon has been slowly, slowly building up.”
When the permafrost melts microbes gain access to these carbons that were previously out of bounds because they were frozen. The Arctic permafrost, where deep layers of soil remain frozen all year round, is estimated to contain 1,500 billion tons of carbon – about twice as much as is currently contained in the atmosphere.
In pictures: Changing climate around the world
In pictures: Changing climate around the world
Calved icebergs from the nearby Twin Glaciers are seen floating on the water in Qaqortoq, Greenland
Oroumieh, one of the biggest saltwater lakes on Earth, has shrunk more than 80 percent to 1,000 square kilometers in the past decade. It shrinks mainly because of climate change, expanded irrigation for surrounding farms and the damming of rivers that feed the body of water
A boat navigates among calved icebergs from the nearby Twin Glaciers in Qaqortoq, Greenland. Boats are a crucial mode of transportation in the country that has few roads. As cities like Miami, New York and other vulnerable spots around the world strategize about how to respond to climate change, many Greenlanders simply do what theyve always done: adapt. 'Were used to change, said Greenlander Pilu Neilsen. 'We learn to adapt to whatever comes. If all the glaciers melt, well just get more land
The Svalbard Global Seed Vault is seen after being inaugurated in Longyearbyen, Norway. The 'doomsday' seed vault built to protect millions of food crops from climate change, wars and natural disasters opened deep within an Arctic mountain in the remote Norwegian archipelago of Svalbard
A technician preparing to drain a vast underground lake at the Tete Rousse glacier on the Mont Blanc Alpine mountain, to avert a potentially disatrous flood. Some 65,000 cubic metres (2.3 million cubic feet) of water have gathered in a cavity, dangerously raising the pressure beneath the mountain, a favourite spot for holiday makers in Saint-Gervais-les-Bains
Cracked mud is picture at sunrise in the dried shores of Lake Gruyere affected by continuous drought near the western Switzerland village of Avry-devant-Pont. A leading climate scientist warned that Europe should take action over increasing drought and floods, stressing that some climate change trends were clear despite variations in predictions
Cattle graze on grassland that remains dry and brown at the height of the rainy season in south of Bakersfield, California. Its third straight year of unprecedented drought, California is experiencing its driest year on record, dating back 119 years, and dating back as far as 500 years, according to some scientists who study tree rings
An aerial view shows tents of flood-displaced people surrounded by water in southern Sehwan town. United Nations Framework Convention on Climate Change (UNFCCC) executive secretary Christiana Figueres met with people displaced by last year's devastating floods. Catastrophic monsoon rains that swept through the country in 2010 and affected some 20 million people, destroyed 1.7 million homes and damaged 5.4 million acres of arable land
An aerial view of flooding in North Wagga Wagga. Climate change is amplifying risks from drought, floods, storm and rising seas, threatening all countries but small island states, poor nations and arid regions in particular, UN experts warned
Damages caused by a landslide on the Pan-American highway near La Moramulca, 55 Km south of Tegucigalpa. International highways have been washed out, villages isolated and thousands of families have lost homes and crops in a region that the United Nations has classified as one of the most affected by climate change
A resident sprays water on a peatland fire in Pekanbaru district in Riau province on Indonesia's Sumatra island. Indonesia, an archipelago of 17,000 islands, is one of the world's biggest carbon emitters because of rampant deforestation. US Secretary of State John Kerry Sunday issued a clarion call for nations to do to more to combat climate change, calling it 'the world's largest weapon of mass destruction'
An excavator clearing a peatland forest area for a palm oil plantations in Trumon subdistrict, Aceh province, on Indonesia's Sumatra island. As Southeast Asia's largest economy grows rapidly, swathes of biodiverse forests across the archipelago of 17,000 islands have been cleared to make way for paper and palm oil plantations, as well as for mining and agriculture. The destruction has ravaged biodiversity, placing animals such as orangutans and Sumatran tigers in danger of extinction, while also leading to the release of vast amounts of climate change-causing carbon dioxide
Stagnant rain water with tannery waste make the Hazaribagh area in Old Dhaka as well as Buriganga River the most polluted. Each year during the seven-month long dry season between October and April the Buriganga River becomes totally stagnant with its upstream region drying up and becoming polluted from toxic waste from city industries
Waste water from Dhaka city drained to the River Buriganga contributes to its pollutions. On the World Water Day observed in 2007 under the theme Coping with Water Scarcity, under the leadership of the Food and Agriculture Organization of the United Nations, DrikNEWS explores some of the images of the river. UN-Water has identified coping with water scarcity as part of the strategic issues and priorities requiring joint UN action. The theme highlights the significance of cooperation and importance of an integrated approach to water resource management of water at international, national and local levels
Heavy smog has been lingering in northern and eastern parts of China, disturbing the traffic, worsening air pollution and forcing the closure of schools. China's Environment Ministry said it will send inspection teams to provinces and cities most seriously affected by smog to ensure rules on fighting air pollution are being enforced
Climate scientists are extremely concerned about melting permafrost, which they say could create a “feedback loop” of rising temperatures and increased melting.
A separate study found that the beaver is playing an increasing part in climate change because the dams they build for shelter create shallow, stagnant ponds of water which allow biological material to build up on the bottom of the river.
This is broken down by microbes and released into the atmosphere in the form of methane.
The production of methane is accelerated because stationary pools of water contain much less oxygen than a flowing river interacting with the atmosphere and microbes thrive in low-oxygen environments.
The study, by the University of Saskatchewan in Canada, estimates that beavers are indirectly producing 200 times more methane today than they were in 1900, when fur hunting had largely wiped out the populations in North American, Europe and Asia.
The population rebound, on the back of a conservation drive, has greatly increased the number of “beaver ponds”. They are now responsible for pumping 881,000 tons of methane into the atmosphere each year, according to the research, published in the journal Ambio.
Something to chew on: Impact of ruminants
Rodents and squirrels are not the first animals to be blamed for contributing to climate change – ruminants have long been known to play a role.
The biggest culprit in this department is the cow, which through a combination of burping and breaking wind, and by virtue of its enormous population, produces mind-boggling quantities of methane – estimates vary, but a single cow is thought to produce anything between 250 and 500 litres of methane a day. That’s 55 to 110 gallons.
Overall, the livestock ruminant sector, which is mainly cows but includes animals such as sheep, goats and buffalo, produces 18 per cent of the world’s greenhouse gases, a bigger contribution to climate change than transport.